Palladium(II) aryl-amido complexes of diphosphinoazines in unsymmetrical PNP’ pincer-type configuration

Square planar palladium(II) aryl-amido complexes of diphosphinoazines in monoanionic unsymmetrical PNP’ pincer-type coordination were prepared by reactions of phenyl-, o-tolyl-, or 2,6-dimethylphenyllithium with previously described chloro-amido complexes of diphosphinoazines having isopropyl, cyclohexyl and tert-butyl substituents on phosphorus atoms. The compounds were characterized by NMR showing free rotation around metal–aryl bond in the complexes; the presence of Cipso–Pd bond was detected by two-dimensional experiments. In addition to that, crystal and molecular structure of one phenyl-amido complex, [Pd(C6H5){P(C6H11)2CHdouble bond; length as m-dashC(But)NNdouble bond; length as m-dashC(But)CH2P(C6H11)2}], was determined by X-ray diffraction together with the structure of a chloro-amido complex [PdCl{PBut2CHdouble bond; length as m-dashC(But)NNdouble bond; length as m-dashC(But)CH2PBut2}]. In both structures the ligand trans to the amide nitrogen is well surrounded by substituents on phosphorus atoms, the former complex showing significant interactions between two cyclohexyl hydrogen atoms and the π-system of the phenyl ring. The values od Pd–C and Pd–N bond distances in this complex are the same as those in a monodentate analog [Pd(PMe3)2(C6H5)(NHC6H5)] which contrasts with the different values in a similar PNP symmetrical pincer complex reported in the literature.